By charging and balancing individual cells, you mean group of cells that are connected in parallel (the 4P in 12S4P)? I don't see how or why would you balance individual parallel connected cells, unless you had a different battery configuration.
Simplest "balancers" drain cells that have too high a voltage as you are approaching full charge. You do need to occasionally top the battery off, to keep it balanced. Seeing they already have sense wires and discharge resistors, they could fully monitor state and balance even without top off, but that's additional code complexity.
There are nice BMSs that can shuffle charge between cell groups - they increase range by helping the weakest link, and should help longevity, by again, decreasing strain on the already worst cells. I don't know how common they are, just that they are not typical. There you can also have good and sub-optimal algorithms.
I have heard of individual cell monitoring and maybe balancing, but I have no idea what, how or why it does it.
The pack I built has a balancer, that's what all the red wires on the photograph are for. It uses a charge pump to move some charge around so that the high cells get clipped and the low ones brought up. It keeps the pack within 2 mV. The unit it monitors is the cell group, all 10 of them have a wire to the balancer and a ground for reference. It is very accurate and it wills substantially contribute to the life-span of the pack.
Simplest "balancers" drain cells that have too high a voltage as you are approaching full charge. You do need to occasionally top the battery off, to keep it balanced. Seeing they already have sense wires and discharge resistors, they could fully monitor state and balance even without top off, but that's additional code complexity.
There are nice BMSs that can shuffle charge between cell groups - they increase range by helping the weakest link, and should help longevity, by again, decreasing strain on the already worst cells. I don't know how common they are, just that they are not typical. There you can also have good and sub-optimal algorithms.
I have heard of individual cell monitoring and maybe balancing, but I have no idea what, how or why it does it.